Special Containment Procedures: SCP-726 is to be stored in a titanium safe box, 30 x 30 x 20 cms in size at Site-19, ████ section, secured with a retinal biometric lock to be opened only for testing purposes by Level-4 or higher clearance personnel. SCP-726 must not be run on any computer without authorization from Level 4 personnel or above, and testing must be done in a soundproof chamber; the procedure will be streamed via CCTV and an information-fetching camera will document all SCP-726's output. No storage devices are allowed and all computer equipment used must be destroyed using SCP-compliant destruction protocols immediately after use. Network access is strictly prohibited. Should a researcher need to investigate the SCP, a clearance letter for research must be addressed to Dr. ████████ with copy to Foundation's memberboard.

Description: SCP-726 consist of a DOS Mahjong computer game named "Ether" (no copyright stated), 17 MB in size, stored in a ZIP disk that was found on NASA researcher Dr. ███ ██████████'s computer after he died from suffocation as a result of seizure in his New York residence on █/█1995. Dr. ██████████'s eardrums were massively damaged and his tongue almost severed by his own teeth, but the fact that the disk kept functioning inside the ZIP drive even when the computer was unplugged (according to the official report) has reached the Foundation's interest, and covert agent [DATA EXPUNGED] was able to collect the case evidence and deploy Class-A amnesiacs to the Police Force members involved in this case.

Upon arrival to Site-19, identification and initial research revealed that SCP-726 runs normally until a game is lost. D-Class subject #21135 was instructed to play a round of the game; once he lost, the computer's internal speaker began emitting a high pitch frequency that led to eardrum bleeding and convulsions, followed by a seizure and subject's death along with two researchers that were on site. Analysis of the sound shows a frequency of precisely █████ hertz with underlying elements of low pitch vibration, theorized to block refraction of the sound wave inside the ear canal, leading to excursions of the tympanic membrane that are 100 to 1000 times greater than normal for recorded dB (decibel) levels. As stated before and known after the initial research procedure, removal of any sound synthesis device on the computer is meaningless, since the sound will still be rendered from an unknown source inside the computer being used.

After a series of precautionary measures, reverse engineering procedures began. SCP-726 has no AI for the game itself, but the existence of a neural network of unknown extension has been infered, revealing SCP-726's productive behavior. It has been found that if seventy-two (72) games are won consecutively, SCP-726 will disallow user interaction for 10 minutes and rearrange its pieces in various symmetrical patterns (resembling graphs) and display additional references, chemical components or equations; applications of these patterns have led to the discovery of previously unknown solids, chemical bonds and mathematical phenomena (refer to Addendum I for a declassified list of discoveries based on SCP-726). Once the ten minute lapse is over, SCP-726 will close itself and reboot the computer. It has been confirmed that part of SCP-726's neural network doesn't run in the operative system's memory and RAM, thus not allowing further debugging on it.

Suggestions to use SCP-079 as a test subject because of its processing capacity and artificial nature have been refused; instead, an SCP-894-2 copy is to be placed near the D-class subject involved in testing and once the pattern is recorded, medical checks and class-B amnesiacs must be deployed on the subject. An attempt to play using an AI created by Foundation researchers has been made and failed; it's been theorized that SCP-726 deploys a pattern identification on user's input for identifying human presence, although it seems not to be aware of deafness in subjects. (See log #726-1A for details)

Addendum I - List of SCP-726 knowledge-based discoveries

Preliminary note: these technologies are currently being deployed internally. Leakage or disclosure of any technology listed here will be punished with termination.

Valogel, a stronger variant of aerogel. Production for SCP-enabled containment devices is scheduled.

Partial demostration of the Continuum Hypothesis (complete demostration was achieved at the Foundation's R+D facilites in ██/██/2001)

Poiesil protein - Successfully proven to regenerate damaged spinal cords, nerves and able to restore 83% of lost neuroplasticity. Testing phase in progress.

Document log #726-1A: Simulation of a human player using AIDate: ██/██/1996Test subject: SCP-726

Preliminary note: AI and SCP-726 execution was earlier scheduled to run on system startup. No humans were present at this experiment's beginning.

On-screen quote: "I only play against flesh." and a blinking cursor appears on screen.

[High-frequency pitch starts, then stops once the deafened subject D-3271 enters the room, having been previously instructed to interact with SCP-726. Subject instinctively presses Enter key and starts playing.]

[After ten moves] On-screen quote: "Thank you."

[Game continues]

[After 9 (nine) minutes, game finishes with subject D-3271 being carried out quickly of the chamber with auricular hemorrhage and taken to the internal medical facility. The hemorraghe is stopped and the subject is stabilized, althought the tympanic membrane is 30% damaged. After the SCP-894-2 effect disappeared, Class-B amnesiacs are given and the subject is realocated for further testing at other SCP research facilities.]

Notes: It is now known that once SCP-726 is started, the game is loaded to RAM memory and needs no access to the ZIP drive; every attempt to terminate the running instance has failed thus it will keep running until the game either is won or lost.